It is not easy to design systems using RF-linked tags to achieve visibility. It would be desirable to have systems that permit day-to-day functions to be achieved without the need for communications back to a central server to facilitate seemingly simple tasks. It would be desirable to have systems that scale well, and that work even with steel and water nearby. For many visibility tasks it would be very helpful to have system structure permitting knowledge of types of products or product taxonomy.
Staggering amounts of money and toil have been devoted to efforts to devise such systems. Despite this, no present-day system of RF tags has come anywhere close to satisfying such goals.
Both passive and active RF-ID tags now on the market use non-radiating backscattered mode, and all work as transponders, i.e they all need a carrier and do not work well around steel or water and cannot be networked.
The current standard EPC RFID tags all have a pre-assigned or assigned fixed ID serial number with some data encoded. It may include a header. Different formats are allowed, for example the DoD has 256 bits to define its UID (Universal Identification) versus 96 bits for all consumer goods. The CG scheme after the 8 bit header follows the current Global Trade Identification Number format of country code (2 digits); Manufacturer code 4 or 5 digits; Product Code 5 digits; and finally a serial number of 30 bits. There are possible categories for manufacturer's name but none for types of products or for product taxonomy.
Often, this serial number is created when the tag itself is manufactured. With other tag technologies the serial number is written when the product is packaged. In either case, it will be appreciated that with current RFID tags and tag networks that meet EPC global standards, the systems depend on addressing schemes based on fixed arbitrary numbers often 96-128 bits long. This also requires that key product data and information be stored in remote IT systems. An analogy is shown in FIG. 1, part A. Packages are be identified and encoded with a unique number with all information about “ship to”, “ship from”, and “packing slip” encoded in (and pointed to by) a number. Such systems generally require that all detailed data may be contained on a server with a key or pointer based on the encoded number.
Such systems have many drawbacks. Chief among the many drawbacks is that the system requires message-passing back to a central server and from the central server back to the user location, for even the simplest visibility task. The message passing requires bandwidth, sometimes a lot of bandwidth, both in the communications channels and in the central database, to keep up with system activity. Disruption of the communications channels brings the entire system grinding to a halt.